1. Field of the Invention
The present invention relates to a barcode reading apparatus, which is provided in a test tube transfer path to transfer a test tube with a barcode label from a test tube rack to an inspection apparatus.
2. Description of the Related Art
A test tube containing a sample such as blood is labeled with a barcode indicating components of the sample, density and amount of a main component, etc. The barcode is read with a barcode reader provided in a test tube transfer path, and sent to an inspection apparatus or the like in a later stage as information for control or instruction in a subsequent process.
FIG. 1 and FIG. 2 show the side view and plane view of a conventional test tube barcode reader. A test tube holder 103 holds vertical a test tube 101 with a barcode label 102 in the upper periphery. The test tube holder 103 is held vertical and transferred by a transfer mechanism 105. The transfer mechanism 105 is provided with a barcode reader 109 at a barcode reading position to read the bar code 102 of the test tube 101. On the opposite side of the barcode reader 109 of the transfer mechanism 105, a test tube holder rotating mechanism 110 is provided to face the barcode 102 of the test tube 101 to the barcode reader 109 by pressing a roller to the outer periphery of the test tube holder 103 and rotating the test tube holder 103 in this state.
The test tube holder 103 comprises a cylinder 104 having a pair of flanges 104a and 104b on the lower periphery, and an annular groove 104c between the flanges. A leaf spring (not shown) is provided in the cylinder 104 to insert and hold the test tube 101 vertical.
The transfer mechanism 105 comprises a belt conveyer 106 which holds a number of test tube holders 103 vertical and conveys them intermittently at a regular intervals, and guide rollers 107 and 108 which have guide projections 107a and 108a to engage with the annular groove 104c of the test tube holder 103 with a play, and are provided on both sides of the belt conveyer 106.
The test tube holder rotating mechanism 110 comprises a pair of friction rollers 111 and 112 which are supported rotatably around the vertical axis of a guide rail 107 on one side of the rotating mechanism and pressed to one side of the periphery of the cylinder 104, an endless belt 113 which is wound around the pulleys of friction rollers 111 and 112 and rotates the friction rollers 111 and 112 together in the direction of the arrow in FIG. 2, and a drive motor 114 which drives and rotates the friction roller 111. The test tube holder rotating mechanism 110 is configured to read the barcode 102 of the test tube 101 faced to the bar code reader 109, by rotating the test tube 101 held by the test tube holder 103 by pressing the friction rollers 111 and 112 to the periphery of the holder cylinder 104 from one side and rotating the test tube holder in this state.
However, an idle clearance is formed in the engagement between the guide projections 107a/108a of the guide rails 107/108 and the annular groove 104c formed between the flanges of the test tube holder 103, as shown in FIG. 1. Thus, if the test tube holder 103 is rotated in the state that the friction rollers 111 and 112 are pressed to the periphery of the cylinder from one side, the test tube holder 103 and test tube 101 held thereby swing as indicated by a broken line in FIG. 1, or the flanges 104a and 104b of the test tube holder 103 are pressed strongly to the insides of the guide rails 107 and 108 or the guide projections 107a and 108a. In this state, the test tube holder 103 and test tube 101 held thereby cannot be rotated, and the barcode 102 cannot be faced exactly to the barcode reader 109. As a result, a problem of failing to read the barcode 2 occurs.